Re: WAL files not being recycled

On 05/16/2016 03:33 PM, Scott Moynes wrote:
> I have a PostgreSQL server that is not recycling WAL files. Log files
> are continually created and no old log files are ever removed.
>
> Running PostgreSQL v 9.4.8 with archive settings:
>
> archive_mode = on
> archive_command = /bin/true
>
> Checkpoint logging is enabled and does not record any logs being recycled:
>
> 2016-05-16 00:05:37 EDT - LOG: checkpoint starting: xlog
> 2016-05-16 00:09:51 EDT - LOG: checkpoint complete: wrote 38574
> buffers (29.4%); 0 transaction log file(s) added, 0 removed, 0 recycled;
> write=252.921 s, sync=1.340 s, total=254.312 s; sync files=48,
> longest=1.101 s, average=0.027 s
> 2016-05-16 00:10:37 EDT - LOG: checkpoint starting: time
> 2016-05-16 00:14:11 EDT - LOG: checkpoint complete: wrote 43786
> buffers (33.4%); 0 transaction log file(s) added, 0 removed, 0 recycled;
> write=206.271 s, sync=7.428 s, total=213.765 s; sync files=82,
> longest=3.821 s, average=0.090 s
> ...
> 2016-05-16 07:32:27 EDT - LOG: checkpoint complete: wrote 7617
> buffers (5.8%); 1 transaction log file(s) added, 0 removed, 0 recycled;
> write=269.3
>
> Control data records:
>
> pg_control last modified: Mon 16 May 2016 06:23:07 PM EDT
> Latest checkpoint location: 1EB/1F008FE8
> Prior checkpoint location: 1EB/1E0009E0
> Latest checkpoint's REDO location: 1EB/1F008FB0
>
> There is a single replication client:
>
> pid | 23287
> usesysid | 10
> usename | postgres
> application_name | walreceiver
> client_addr | 172.16.56.246
> client_hostname |
> client_port | 58070
> backend_start | 2016-05-14 03:27:33.523611+00
> backend_xmin |
> state | streaming
> sent_location | 1EB/1F042760
> write_location | 1EB/1F042760
> flush_location | 1EB/1F042760
> replay_location | 1EB/1F037F40
> sync_priority | 0
> sync_state | async
>
>
> Does anyone have suggestions what else to check? What can cause WALs not
> to be recycled or removed?

http://www.postgresql.org/docs/9.4/interactive/runtime-config-replication.html#RUNTIME-CONFIG-REPLICATION-MASTER

"wal_keep_segments (integer)

Specifies the minimum number of past log file segments kept in the
pg_xlog directory, in case a standby server needs to fetch them for
streaming replication. Each segment is normally 16 megabytes. If a
standby server connected to the sending server falls behind by more than
wal_keep_segments segments, the sending server might remove a WAL
segment still needed by the standby, in which case the replication
connection will be terminated. Downstream connections will also
eventually fail as a result. (However, the standby server can recover by
fetching the segment from archive, if WAL archiving is in use.)

This sets only the minimum number of segments retained in pg_xlog;
the system might need to retain more segments for WAL archival or to
recover from a checkpoint. If wal_keep_segments is zero (the default),
the system doesn't keep any extra segments for standby purposes, so the
number of old WAL segments available to standby servers is a function of
the location of the previous checkpoint and status of WAL archiving.
This parameter can only be set in the postgresql.conf file or on the
server command line.
"

>
> Thanks in advance.
>
> --
> Scott Moynes
> VM Farms

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com